A unique solar pond system integrated with chlor-alkali electrolyser for heat storage and hydrogen production

Abstract

Solar ponds are recognized as a simple, but unique solution for renewable heat storage to use later. The freshwater feed to solar ponds is considered a crucial requirement to maintain the salinity gradient accordingly for heat storage purposes. This study aims to benefit from this specific requirement for solar ponds by integrating chlor-alkali electrolysers to produce hydrogen along with heat storage, which is a common output of a solar pond. Therefore, the proposed system establishes a desirable synergy, as per the sustainable development goals, between a conventional solar pond and an innovative high-tech hydrogen production system. In order to produce hydrogen, the saline water withdrawn from the upper convective zone is used in a chlor-alkali electrolyser powered by solar PV in order to produce green hydrogen. Thus, a conventional solar pond is converted into an integrated energy system that produces hydrogen and chlorine for useful purposes, along with heat storage capability. The system’s performance has been assessed in terms of energy and exergy efficiencies for five distinct cities located in different countries that are grappling with poverty. The system’s performance, assessed in five cities, demonstrates the energy and exergy efficiencies ranging from 11.66 % to 14.56 % and 6.84 % to 8.60 % for the solar pond, and 21.95 % to 24.22 % and 14.23 % to 14.66 % for the overall system, respectively. The system effectively captures and stores solar energy, reaching temperatures up to 89.1 °C. The proposed system contributes to the UN’s Sustainable Development Goals by addressing energy poverty, promoting clean energy, and fostering economic growth.